"Here there is good and bad news. Yes, we can run the world on renewables and efficiency. Any self-respecting solar energy company--hooked up with the right partners--can put up zero carbon buildings in a matter of weeks. Around 50% of CO2 emissions come from buildings, directly or indirectly. Meanwhile, as traditional power prices soar, solar manufacturing costs are falling."On the other hand, he doesn't hold back from his warnings that, if the worst predictions of the peak oil community are correct, we are in for some very rough times. He talks of a profound and lasting energy crisis that will "dwarf previous crises", and suggests the only thing to do is to mobilize now with all possible renewable and efficiency technologies as if for war. Of course, Leggett has a certain interest in promoting such a massive mobilization, given the work his company is doing with solar for schools, office buildings and homes, but as the evidence of impending climate and energy crises keeps mounting, we find it hard to disagree with him. What are we waiting for?